As technology has evolved, handheld battery powered electronic devices, such as cellular phones and tablets, have grown in functionality, processing power, and screen resolution. As consumers now spend greater periods of time using these devices than in the past, a market desire for such devices to have a long battery life has emerged. At the same time, however, to ease the portability and enhance the aesthetics of such devices, a market desire for such devices to be as small as possible for a given screen size has emerged. These market desires can be at odds with each other, as a simple way to increase battery life is to increase the size of the battery in the device, however, such an increase in battery size may result in an increase in the size of the device itself.
One way to increase the battery life of a device that may not result in an increase in size of the device may be to reduce the power consumption of the device. To that end, such devices may switch between an active mode in which the device is actively performing functions, and a standby mode in which the device is passively performing functions, or even not performing functions. Since such devices spend may more time in the standby mode than the active mode, a reduction of power consumption in the standby mode may result in a significant increase in battery life.
These electronic devices may employ a power supply to power their circuitry. The power supply may convert the output of the battery into consistent and usable power, and in some cases, a switching power converter may be employed as the power supply. Such a switching power converter may employ a pulse-width modulation (PWM) technique to control the power delivered to the circuitry in the active mode. While PWM may be efficient for controlling the power delivered to the circuitry in the active mode, a different modulation technique may be desirable for controlling the power delivered to the circuitry in the passive mode. For example, a pulse frequency modulation (PFM) mode or a pulse skipping modulation (PSM) mode may be desirable for control of the power delivered to the circuitry in the passive mode, as these modes may be able to sufficiently operate the circuitry in the passive mode while delivering less power than would be delivered by a PWM technique, thereby decreasing power consumption.
Fine control of the transition threshold of the switching converter between PWM and PFM/PSM modes can help to further reduce power consumption, and thus increase battery life of the device. To that end, developments in circuitry to finely control this transition threshold are desired.